Corner construction for folding boxes



P 1962 c. J. PIERCE, JR 3,053,429

CORNER CONSTRUCTION FOR FOLDING BOXES Filed Sept. 1, 1960 2 Sheets-Sheet l INVENTOR.

Cbesfer .1 Pierce, Jr.

M WM ATTORNEY Sept. 11, 1962 c. J. PIERCE, JR

CORNER CONSTRUCTION FOR FOLDING BOXES 2 Sheets-Sheet 2' Filed Sept. 1, 1960 Fig. 4

INVENTOR. Chesfer J Pzerce, Jr.

Arrow Patented Sept. 11, 1962 3,053,429 CORNER CONSTRUCTION FOR FOLDING BOXES Chester J. Pierce, .lr., Palo Alto, Calif., assignor, by mesne This invention relates to improvements in the corner construction of gluelessly interlocked folding boxes of the type in which -a lock flap articulated to one wall panel is folded over the next wall panel and is partially inserted into a slit in the latter. The lock fiap is provided with a locking edge which engages an edge of the slit and thus prevents withdrawal of the lock flap from the slit.

In order to prevent accidental disengagement of the lock, the lock flap may be provided with a projecting portion extending beyond the confines of the deflectable tongue formed in the slotted wall panel, so that the projecting portion must be forceably moved through the slit into the interior of the box in which position the projection forms a safety catch resisting accidental disengagement. Locks of this type form the subject matter of the patent to R. B. Meller, 2,580,181, dated December 25, 1951. These locks offer the further advantage of permitting rapid forming and locking by an automatic mechanism as disclosed in the patent to E. I. Pagendarm, 2,5 80,- 189, dated December 25, 1951. The mechanism comprises basically a blank folding die and a plunger which forces the originally fiat blank through the die, thereby forming and engaging the corners. The plunger is fitted with movable fingers which first open the wall slits, grasp the portion of the lock flap on which the safety catch is formed, and then pull the flap portion to the inside of the box. Thereafter the completed box is stripped off the plunger. This requires that the lock flaps are so formed and the safety catches so disposed with respect to the movable fingers that the box is readily disengaged. It follows that the safety catch is only practical if it is so shaped and placed that the forming and removal of the box is not interfered with.

The illustrations in the aforesaid Meller patent show the lock tip which represents the safety catch as extending above the internal out which forms the internal tongue in the side wall.

If boxes are extremely shallow, the space available for the internal cut and the lock tip thereabove is so limited that it is difiicult to accommodate both within the limited height of the box wall without reducing the size of the lock to such small dimensions as to make it unreliable.

The present invention provides an improved form of lock in which the entire height of the wall is available for the lock proper and in which the safety catch is so placed as not to add to the height of the construction, yet so located as to be operable by the fingers of the plunger and to permit withdrawal of the box therefrom.

If the box is fitted with a flap extending from the top of the slotted wall, for example a dust flap, the internal cut may extend the full height of the wall up to the hinge line of the flap.

The various features and advantages of this invention will appear more fully from the detailed description which follows accompanied by drawings showing, for the purpose of illustration, preferred embodiments of this invention. The invention also resides in certain new and original features of construction and combination of elements hereinafter set forth and claimed.

Although the characteristic features of this invention which are believed to be novel will be particularly pointed out in the claims appended hereto, the invention itself, its objects and advantages, and the manner in which it may be carried out may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part of it in which:

FIG. 1 is a plan view of a corner portion of a box blank;

FIG. 2 is a perspective view of a partially assembled corner formed from the blank of FIG. 1;

FIG. 3 is an elevational View of a portion of the corner, the section being taken on line 3---3 of FIG. 2;

FIG. 4 is a plan view of a corner portion of a modified blank; and

FIG. 5 is a perspective view of a box corner assembled from the blank of FIG. 4.

In the following description and in the claims various details will be identified by specific names for convenience. The names, however, are intended to be generic in their application. Corresponding reference characters refer to corresponding parts in the several figures of the drawings.

The drawings accompanying, and forming part of, this specification disclose certain specific details of construction for the purpose of explaining of the basic aspects of this invention, but it is understood that structural details may be modified in various respects without departure from the principles of the invention and that the invention may be incorporated in other structural forms than shown.

The corner portion of the folding box blank A comprises a main panel 11 to which a first wall panel 12 is articulated along a first fold line 13. The main panel may represent the bottom of a box body or the top panel of a cover, or any other portion of a box.

A second wall panel 14 is articulated to the main panel 11 along a second fold line 15 extending at an angle to the fold line 13 which it meets at a point of intersection 16. A look flap 17 is articulated to the second panel 14 along a corner fold line .18.

An internal cut 19 is formed in the first panel 12 and comprises a top portion 2t) substantially parallel to the first fold line 13, a first slanted portion 21 downwardly extending from the top portion 241 in the general direction of the box corner point 16, and a second slanted portion 22 extending at an angle to the first slanted portion 21. The internal cut 19 delineates an internal tongue 23 in the panel 12 which yields readily to a force exerted in a direction normal to the surface of the board in order to open the cut '19 and permit the lock flap 17 to enter.

The lock flap 17 has an angular external cut 24 extending into it from its top edge 25. The cut comprises a first portion 26 which may be substantially upright with respect to the main panel 11 in the assembled corner or, in other words, substantially parallel to the corner fold line 18. A second portion 27 of the cut 24 extends at an angle to portion 26 and preferably runs in the general direction towards the corner point 16.

In forming the box corner A, the internal tongue 23 is outwardly deflected and the lock flap inserted into the opened slit 19. This operation, per se, leaves a portion 28 of the lock flap outside the panel. This portion is bounded by the top edge 25 of the lock flap 17 and the upright cut portion 26.

FIG. 2 shows the corner A partially completed except for the position of the tip 28 which still lies on the outside of the wall panel 12. The assembly mechanism next engages the end of the lock flap 17 and flexes it to the inside of the box corner, whereby the tip 28 resiliently snaps past the portion 21 of the cut into the position in which it is shown in FIG. 3. -In the fully locked position a portion of the internal cut 21 engages a portion of the external cut 27 along an engagement zone 29 which may be made longer or shorter, as desired, by suitable configuration of the cutS. The engagement zone lies below the tip 28 which acts as a safety catch to prevent accidental disengagement of the interlocking cut portions 21 and 27.

As described in greater detail in the aforementioned Pagendarm patent, the device for opening the internal cut 19 in the wall panel 12 may be a movable finger or blade on the box forming plunger which is first projected to flex the internal tongue 23 outwardly so as to open the cut 19 and permit the lock flap 17 partially to enter underneath the blade or finger indicated in FIG. 2. As soon as the corner is squared, the finger or blade 30 is pulled to the inside of the corner, thus forcing the tip 28 to move into safety catch position. It is readily seen from FIG. 2 that subsequent disengagement of the box from the plunger is not hindered in any way by either the lock flap or its safety catch tip 28. The direction of travel of the blade 30 relatively to the 'box is indicated by broken lines 31 in FIG. 2.

FIG. 4 shows the corner portion of a modified blank corresponding in most details to the blank portion shown in FIG. 1. In order to avoid the necessity of describing corresponding blank portions, numerals are applied t 'blank B which differ from those in blank A by 100. Thus main panel 111 corresponds to main panel 11, wall panel 112 corresponds to panel 12, etc. The following distinctions should be noted. The wall panel 112 has a dust flap 32 articulated to it along a fold line 33. The internal cut 119 has a top portion 120 which coincides with the fold line 33, thus utilizing the full height of the panel 112 for the internal cut 119.

The panel 114 is in the nature of a box back panel and has a cover panel 34 articulated to it along a cover fold line 35. The cover panel 34 is provided with a side flap or charlotte 36 articulated to the cover panel along a charlotte fold line 37.

The fully locked corner B is shown in FIG. 5. the illustrated condition the dust flap 32 is still upright and the charlotte 36 is still extended, it being understood that both will be folded when the box is closed after filling.

A typical box of which FIGS. 4 and represent a corner has a bottom dimension of approximately x 6 /2 inches and a height of only /2 inch, making it a rather shallow box. It is reliably assembled by the corner lock construction herein disclosed.

Obviously, the configuration of the locking cuts may be modified without departure from the spirit of the invention.

Whatiis claimed is:

1. The corner construction for folding boxes which comprisesla main panel; a first wall panel articulated to the mainpanel along a first fold line; a second wall panel articulated/to the main panel along a second fold line extending at an angle to said first fold line; a lock flap articulated to said second wall panel along a corner fold line upwardly extending from the intersection of said first and second fold line in the assembled corner, said first wall panel having an internal cut therein forming an internal tongue pointing towards the corner, said internal cut comprising a top portion substantially parallel to said first fold line, a first slanted cut portion downwardly extending from said top portion towards said intersection, and a second slanted portion below the first slanted portion extending at an angle to the first slanted portion, the lock flap having an external cut extending into it from its top edge, said external cut being angular and coinciding within one portion of its length with a portionof said internal cut, another portion of the external cut forming a lock tip overlying the said first panel with in the area between said internal tongue and said corner fold line, the said tip extending no higher than said top portion and being resiliently forceable from a position outside the first panel through the internal cut into a position in which it overlies the first panel on the inside of the corner in which position the said coinciding portion of the external cut engages said first slanted portion of the internal cut.

2. The corner construction for folding boxes which comprises a main panel; a first wall panel articulated to the main panel along a first fold line; a second wall panel articulated to the main panel along a second fold line extending at an angle to said first fold line; a lock fiap articulated to said second wall panel along a corner fold line upwardly extending from the intersection of said first and second fold line in the assembled corner, said first wall panel having an internal cut therein forming an internal tongue pointing towards the corner, said internal cut comprising a top portion substantially parallel to said first fold line, a first slanted cut portion downwardly extending from said top portion towards said intersection, and a second slanted portion below the first slanted portion extending at an angle to the first slanted portion, the lock flap having an external cut extending into it from its top edge, said external cut being angular and coinciding within one portion of its length with the said first slanted portion of said internal cut, another portion of the external cut forming a lock tip above said coinciding portion, said tip overlying said first panel within the area between said internal tongue and said corner fold line, the said tip extending no higher than said top portion and being resiliently forceable from a position outside the first panel through the internal cut into a position in which it overlies the first panel on the inside of the corner in which position the said coinciding portion of the external cut engages said first slanted portion of the internal out below said tip.

3. The corner for folding boxes which comprises a main panel; a first wall panel articulated to the main panel along a first fold line; a second wall panel articulated to the main panel along a second fold line extending at an angle to said first fold line; a lock flap articulated to said second wall panel along a corner fold line upwardly extending from the intersection of said first and second fold line in the assembled corner, said first wall panel having an internal cut therein forming an internal tongue pointing towards the corner, said internal cut comprising a top portion substantially parallel to said first fold line, a first slanted cut portion downwardly extending from said top portion towards said intersection, and a second slanted portion below the first slanted portion extending at an angle to said first slanted portion, the lock flap having an external cut extending into it from its top edge, said top edge being disposed substantially parallel to said first fold line, said external cut comprising two angularly disposed portions, one of which points in the general direction of said intersection, coincides with at least a portion of said first slanted portion of the internal cut and constituting an engagement portion, the other portion of the external cut extending substantially upright with respect to the said first fold line and forming the front edge of a lock tip, the top edge of the lock tip being formed by the said top edge of the lock flap, the lock tip overlying the said first panel within the area between said internal tongue and said corner fold line, the said tip being resiliently forceable from a position outside the said first panel through the internal cut into a position on the inside of the box corner in which position the said engagement portion of the external cut engages the first slanted portion of the internal cut below said tip, and the tip projects beyond the said slanted first internal cut portion above said engagement portion.

4. The corner construction for folding boxes which comprises a main panel; a first wall panel articulated to the main panel along a first fold line; a second wall panel articulated to the main panel along a second fold line extending at an angle to said first fold line; a top flap articulated to the top of said first panel along a top flap fold'line substantially parallel to said first fold line; a lock flap articulated to said second wall panel along a corner fold line upwardly extending from the intersection of said first and second fold line in the assembled corner, said first wall panel having an internal cut therein forming an internal tongue pointing towards the corner, said internal cut comprising a top portion substantially coinciding with said top fiap fold line, a first slanted cut portion downwardly extending from said top portion towards said intersection, and a second slanted portion below the first slanted portion extending at an angle to the first slanted portion, the lock flap having an external cut extending into it from its top edge, said top edge being disposed substantially parallel to said first fold line, said external out being angular and coinciding Within one lineal portion of its length with a portion of said internal out, another portion of the external cut forming a lock tip overlying the said first panel within the area between said internal tongue and said corner fold line, the said tip being resiliently forceable from a position outside the said first panel through the internal cut into a position on the inside of the box corner in which position a portion of the external out below said tip engages at least a portion of the said first slanted portion, and the tip projects beyond the said slanted first internal cut portion above said engagement portion.

5. The corner construction for folding boxes which comprises a, main panel; a first wall panel articulated to the main panel along a first fold line; a second wall panel articulated to the main panel along a second fold line extending at an angle to said first fold line; a top flap articulated to the top of said first panel along a top flap fold line substantially parallel to said first fold line; a lock flap articulated to said second wall panel along a corner fold line upwardly extending from the intersection of said first and second fold line in the assembled corner, the

said first wall panel having an internal cut therein forming an internal tongue pointing to the corner, said internal cut comprising a top portion substantially coinciding with said top flap fold line, a first slanted portion downwardly extending from said top portion towards said intersection and a second slanted portion below said first slanted portion extending at an angle to said first slanted portion, the lock flap having an external cut extending into it from its top edge, said top edge being disposed substantially parallel to said first fold line, said external cut comprising two angularly disposed portions, one of which points in the general direction of said intersection, coincides along a lineal portion with at least a, portion of said first slanted portion of the internal cut and constitutes an engagement portion, the other portion of the external cut extending substantially upright with respect to the said first fold line and forming the front edge of a lock tip, the top edge of the lock tip being formed by the said top edge of the lock flap, the lock tip overlying the said first panel within the area between said internal tongue and said corner fold line, the said tip being resiliently forceable from a position outside the said first panel through the internal cut into a position on the inside of the box corner in which position the said engagement portion of the external cut engages the first slanted portion of the internal out below said tip, and the tip projects beyond the said slanted first internal cut portion above said engagement portion.

References Cited in the file of this patent UNITED STATES PATENTS 1,544,311 Grafienberger June 30, 1925 2,646,916 Meller July 28, 1953 2,712,409 Buttery July 5, 1955 

